Malachite

malachite (măl`əkīt), a mineral, the green basic carbonate of copper occurring in crystals of the monoclinic system or (more usually) in masses. It is translucent or opaque; the luster is silky, vitreous, adamantine, or dull. It takes a good polish. An important ore of copper, it also serves as a gem and for various ornamental purposes and, when finely ground, as a pigment. It is found associated with other ores of copper (especially azurite) in various parts of the United States and in Chile, Russia, Congo (Kinshasa), Zimbabwe, and Australia.

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malachite

Widespread carbonate mineral of copper, a hydrous copper carbonate, Cu₂CO₃(OH)₂. Because of its distinctive, bright green colour and its presence in the weathered zone of nearly all copper deposits, malachite serves as a prospecting guide. It is found in Siberia, France, Namibia, and Arizona. Malachite has been used as an ornamental stone and as a gemstone.

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malachite

a bright green mineral, found in veins and in association with copper deposits. It is a source of copper and is used as an ornamental stone. Composition: hydrated copper carbonate. Formula: Cu₂CO₃(OH)₂. Crystal structure: monoclinic

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malachite [′mal·ə‚kīt]

(mineralogy)

Cu₂CO₃(OH)₂A bright-green monoclinic mineral consisting of a basic carbonate of copper and usually occurring in massive forms or in bundles of radiating fibers; specific gravity is 4.05, and hardness is 3.5-4 on Mohs scale.

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malachite

A carbonate of copper; green in color; harder than marble; usually employed as a highly polished veneer.

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malachite

guards wearer from evil spirits, enchantments. [Gem Symbolism: Kunz, 97]

See : Protection

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Malachite

a carbonate mineral; composition Cu₂[Co₃] (OH)₂ and containing 57.4 percent Cu. Additional (OH)^1— anions in the crystalline structure of malachite are bonded to Cu²⁺ ions, which are surrounded in one plane by two (OH)^1— and two O²⁺ ions belonging to the (CO₃)^2- carbonate anion. The most common admixtures are Zn (which isomorphically substitutes for Cu), CaO, SiO₂, and Fe₂O₃.

Malachite crystallizes in the monoclinic system. Crystals, which are acicular or prismatic, are rare. Common formations of malachite are cryptocrystalline or microcrystalline reniform incrustations and stalactitic aggregates, which are evenly banded and divergently fibrous. Earthy malachite masses are known as green copper carbonates. The color of malachite ranges from bright green and bluish green to dark green and sometimes even brownish green. The changes that occur in color in the various zones and layers of reniform masses of malachite create very beautiful and fanciful designs along cut and polished planes. Malachite has a hardness of 3.5-4.0 on Mohs’ scale and a density of 3,900-4, 100 kg/m³.

In nature, malachite occurs in the upper oxidized zones of sulfide copper ores. Large accumulations of solid malachite are extremely rare and form during the replacement of limestone by copper sulfate in the oxidation zone of massive copper deposits. Such accumulations (up to 50 m) were worked in the Urals (in the vicinity of Nizhnii Tagil) during the 18th and 19th centuries; other deposits containing ornamental malachite are located in Chile. Solid malachite is a valuable ornamental material and is used to make jewelry and decorative objects (insets, beads, veneer for table tops, vases, column facings). Large articles are faced with thin malachite plates, which are matched according to design and pasted onto a matrix made of metal or other material (“Russian mosaic”). All ornamental objects and large articles are usually fashioned from Ural malachite (The Hermitage in Leningrad, various palace-museums in the USSR and other countries).

Earthy malachite and small accumulations of the pure mineral are used in the manufacture of the valuable paint known as malachite green. Malachite occurring in mixed oxidized ores is used in the smelting of copper.

G. P. BARSANOV